Combined Weak Lensing and X-Ray Search for Galaxy Clusters and the Filaments Connecting Them

Abstract

The work presented here has four main parts. <br /> (1) A newly developed, almost fully automated data reduction pipeline for optical single- and multi-chip CCD cameras is described. Its image products are compared to those against reduced images produced from an independently developed pipeline. The comparison shows very good agreement between both pipelines. <br /> (2) The theory of cosmic structure formation predicts a filamentary large-scale structure of the Universe. These filaments have been observed in large scale redshift surveys for some time. Here we present an attempt to map such a filament between the close pair of massive galaxy clusters A 222/223 using weak gravitational lensing. A mass bridge connecting both clusters is seen in a mass reconstruction making this system only the third known candidate for such a filamentary structure observed with weak lensing. <br /> (3) A public imaging survey following-up on deep XMM-Newton exposures was carried out as collaboration between ESO, the XMM-Newton Survey Science Centre, and the University of Bonn. We present the reduced and calibrated data released from this survey in July 2005. <br /> (4) A combined X-ray, optical matched filter, and X-ray search for clusters of galaxies is carried out on the XMM-Newton Follow-Up Survey. We develop and test our selection criteria for the weak lensing search using ray-tracing simulations through N-body simulations. With the adopted selection criteria we find 28 significant weak lensing peaks that positionally coincide with either X-ray or optical matched filter selected cluster candidates, or correspond to previously known clusters.